static int sumMinus(int a[], int len)
  {
    int sumEven = 0;
    int sumOdd = 0;
		
    for (int i=0; i<len; i++)
    {
      if (a[i]%2 == 0)
        sumEven += a[i];
      else
        sumOdd += a[i];
    }
		
    return sumOdd - sumEven;
  }

